Synucleinopathies are a diverse group of neurodegenerative disorders that share a common pathologic lesion containing abnormal aggregates of insoluble α-synuclein protein in selectively vulnerable populations of neurons and glia. Certain evidence links the formation of abnormal filamentous aggregates to the onset and progression of clinical symptoms and the degeneration of affected brain regions in neurodegenerative disorders including Parkinson's disease (PD), diffuse Lewy body disease (DLBD), multiple system atrophy (MSA), and disorders of brain iron concentration including pantothenate kinase-associated neurodegeneration (e.g., PANK1). The current treatment options for these diseases include symptomatic medications such as carbidopa-levodopa, anticholinergics, and monoamine oxidase inhibitors, with widely variable benefit. Even for the best responders, i.e., patients with idiopathic Parkinson's disease, an initial good response to levodopa is typically overshadowed by drug-induced complications such as motor fluctuations and debilitating dyskinesia, following the first five to seven years of therapy. For the rest of the disorders, the current medications offer marginal symptomatic benefit. Given the severe debilitating nature of these disorders and their prevalence, there is a clear need in the art for novel approaches towards treating and managing synucleinopathies.
Cognitive impairment and dementia are other neurological conditions that are very prevalent and have at times a debilitating nature. Cognitive impairment and dementia may be caused by a variety of factors and disease conditions. For example, cognitive impairment or dementia may be caused by atherosclerosis, stroke, cerebrovascular disease, vascular dementia, multi-infarct dementia, Parkinson's disease and Parkinson's disease dementia, Lewy body disease, Pick's disease, Alzheimer's disease, mild cognitive impairment, Huntington's disease, AIDS and AIDS-related dementia, brain neoplasms, brain lesions, epilepsy, multiple sclerosis, Down's syndrome, Rett's syndrome, progressive supranuclear palsy, frontal lobe syndrome, schizophrenia, traumatic brain injury, post coronary artery by-pass graft surgery, cognitive impairment due to electroconvulsive shock therapy, cognitive impairment due to chemotherapy, cognitive impairment due to a history of drug abuse, attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), autism, dyslexia, depression, bipolar disorder, posttraumatic stress disorder, apathy, myasthenia gravis, cognitive impairment during waking hours due to sleep apnea, Tourette's syndrome, autoimmune vasculitis, systemic lupus erythematosus, polymyalgia rheumatica, hepatic conditions, metabolic diseases, Kufs' disease, adrenoleukodystrophy, metachromatic leukodystrophy, storage diseases, infectious vasculitis, syphillis, neurosyphillis, Lyme disease, complications from intracerebral hemorrhage, hypothyroidism, B 12 deficiency, folic acid deficiency, niacin deficiency, thiamine deficiency, hydrocephalus, complications post anoxia, prion disease (Creutzfeldt-Jakob disease), Fragile X syndrome, phenylketonuria, malnutrition, and neurofibromatosis, maple syrup urine disease, hypercalcemia, hypothyroidism, and hypoglycemia. Dementia is commonly defined as a progressive decline in cognitive function due to damage or disease in the body beyond what is expected from normal aging. Dementia is described as a loss of mental function, involving problems with memory, reasoning, attention, language, and problem solving. Higher level functions are typically affected first. Dementia interferes with a person's ability to function.
Alzheimer's disease (AD) is the leading cause of dementia and cognitive impairment in the elderly and a leading cause of death in developing nations after cardiovascular disease, cancer, and stroke. Up to 70% of cases of dementia are due to Alzheimer's disease, with vascular disease being the second most common cause. The frequency of AD among 60-year-olds is approximately 1%. The incidence of AD doubles approximately every 5 years. Forsyth, Phys. Ther. 78:1325-1331, 1998; Evans et al., JAMA 262:2551-2556, 1989; each of which is incorporated herein by reference. AD afflicts an estimated four million people in the U.S. alone at a cost of $100 billion per year. Schumock, J. Health Syst. Pharm. 55(52):17-21, 1998; Hay & Ernst, Am. J. Public Health 77:1169-1175, 1987; each of which is incorporated herein by reference.
Treatment of cognitive impairment and dementia may be divided into three main areas: pharmacologic interventions targeting the specific underlying pathophysiology; pharmacological agents that ameliorate specific symptoms; and behavioral interventions. The only successful treatments of cognitive impairment in AD to date have been acetyl cholinesterase inhibitors (e.g., tacrine, donepezil, rivastigmine, and galantamine) and NMDA antagonists (e.g., memantine). There remains a need for other pharmacologic approaches in the treatment of synucleopathies and other neurological diseases.